The first episode of a new series is a strange thing, especially as it is often burdened with introducing a new Doctor or companions. It has to juggle introducing the show to potential new viewers, introducing the new character to old ones, providing a quick brush up on the general idea for the forgetful and introducing the first glimmerings of whatever this season's theme and/or arc is going to be. On the whole it is remarkable that so many of them fall into the category of competent if a bit unmemorable, given the temptation to be a huge mess.

Smith and Jones actually has many of the Davies' hallmarks. For instance, as it's central premise, it asks you to swallow a monumentally unlikely idea (a whole hospital gets transplanted to the moon for "jurisdictional" reasons while maintaining structural integrity etc., etc.). It has a police force made out of slightly dim space rhinos largely, one suspects, because who couldn't like space rhino police? rather than as part of any actual coherent attempt at world-building. The new companion exists in a web of family which includes a slightly unreasonable mother but grounds her out in largely believable human interactions.

This is actually a really good episode for Martha. She has yet to develop a crush on the Doctor and I've always felt Freema Agyeman really struggled with Martha's pine-after-the-doctor moments. Agyeman is really much better at portraying a Martha who is brisk, practical and compassionate. NLSS Child warmed to her immediately, announcing a more favourable first impression than Rose had (though I think Clara is still winning in the companion stakes). Since this episode is about introducing Martha she gets to demonstrate all her good points, her medical knowledge, her ability to remain calm under fire and her ability to think on her feet.

Obviously there's a hospital on the moon and somewhat dim space rhino police all existing on the "yes, but" level but these stories work best if you just go with the flow and, on that level, Smith and Jones works well. Like New Earth, it does its job as a season opener and given that isn't the easiest job for a Doctor Who story, it does well to be competent if unremarkable.

Old Who introduces young female companions who start off plucky and independent and end up as screamers.

I sometimes think that New Who replaced this dynamic with young female companions who start off plucky and independent and end up fancying the Doctor.

In this sense, Martha is most like Liz Shaw, in that she clearly starts off as clever and qualified, but then has this Doctor-fancying thing introduced for little real plot reason. Thankfully, she ends well as a character - both in the campaign against the Master and when we see her teaming up with Mickey.

Incidentally, we're currently watching The Rescue, Vicki's first story. I've not seen much of Vicki, but I seem to remember that she is a definite screamer. In this story, she's quite different as an arguably quite disturbed girl (understandably given her background). Maureen O'Brien's acting in the role is really rather good.

Arguably, given their post-traumatic stress, both Susan and Vicki are allowed to scream a lot. Carole Ann Ford works hard to build this into her characterisation, while in Maureen O'Brien's Vicki it fades into an oscillation between adventurousness and clinginess.

If memory serves Maureen O'Brien was very frustrated by her time on Doctor Who. Not just that the character turned out to be very limited but also that it transpired that part of the role of the actress playing the youngest companion was to smooth William Hartnell's ruffled feathers. She obviously didn't feel she'd signed up to baby-sit an older actor.

I think she went on to have a reasonably solid career in theatre but never much liked TV acting.

I absolutely love this episode because it's so fun and adventuresome, while it does a great job of introducing and defining Martha. In general, I think RTD is absolutely fantastic at creating new characters, giving them a life and history, and then introducing them and defining them for us - by the end of the "Rose", "The Christmas Invasion", "Smith and Jones", and "The Runaway Bride", you already pretty much know who these new characters are.

I actually really miss the surreal quality that RTD's episodes have - from the hospital on the moon thing here, to the situation and the people in "Gridlock", to even the rather anachronistic people in "The Fires of Pompeii" (the Caecilius family being so modern-normal and the Cockney street vendor). The classic show and the BF audios sometimes have the same quality, and it draws me to them more than does the current show, which, to me, feels much more standard sci-fi.

I think pp, above, may be correct that, like a lot of classic Who companions, most NuWho companions have good first episodes but then don't necessarily capitalise on their potential. Martha definitely suffered from this and, I think, Clara also - though the character seems to have been salvaged rather last season (I think anyway).

I think its a very difficult line for a show like Dr Who to judge - just how much people will swallow. There are always people, like a friend of a friend I once met who objected to a Robin Hood adaptation because the minarets in Jerusalem in the first scene were incorrect (and you are never going to win over those people), on the other hand there can be a moment when whatever it is you are doing stretches most of the audiences credulity too far. I think both Smith and Jones and Gridlock are just on the right side of that line for Dr Who, but they are both very, very close to it.